With reference to FIG. 1, an example of a conventional medium voltage switchgear is shown generally at 10. As used herein, the terms “medium voltage switchgear” refers to switchgear rated for operation up to and including 15 kV . In general, switchgear 10 comprises an enclosure, such as metal-clad enclosure 12, for housing the switchgear components. Enclosure 12 may contain one or more separate compartments, such as circuit breaker compartment 14, main bus compartment 16, and cable compartment 18. The bus and cable compartments can be formed as a single compartment. Switchgear 10 contains one or more circuit breakers, generally indicated at 20. In the embodiment shown, circuit breaker 20 is a three-pole drawout type circuit breaker. Circuit breaker 20 is connected to primary contacts that are supported by primary conductor bushings 22 that are connected to current-carrying bus bars 24.
In this typical switchgear arrangement, the current transformers 26 are mounted in the circuit breaker compartment 14. The inner diameter of the current transformer 26 has to be large enough to allow the primary conductor bushing 22 to pass through and mount concentrically. The bushing 22 extends through a wall 28 that separates the circuit breaker compartment 14 from the bus and cable compartments 16, 18. As shown in FIG. 2, this arrangement results in large current transformer coils, increasing the phase to phase distance P1 (e.g., greater than 180 mm), the length L1 and the width W1 of the circuit breaker compartment 14 and thus increases the overall dimensions of the switchgear 10.
Thus, there is a need to provide current transformers on bushings in a bus/cable compartment to reduce the phase to phase distance, length and width of the circuit breaker compartment, and thus reduce the overall dimensions of the switchgear.